Project Number: 1932-21630-004-01
Project Type: Specific Cooperative Agreement

Start Date: Sep 01, 2006
End Date: Aug 31, 2009

Objective:
To develop an improved understanding of the role of plant-based polyphenolic compounds, such as tannins, on Appalachian agroecosystems. Specific sub-objectives include: 1) increasing the capability of ARS personnel to measure and characterize tannins and their effects in soil ecosystems; 2) discovery of fundamental information about how tannins and other plant-derived polyphenolic compounds interact with soil and affect the basic fluxes and transformations of soil organic matter and the availability of important plant nutrients such as nitrogen and phosphorus; and 3) synthesis of existing and new data into useful information that provides a rational basis for developing management strategies for soil nutrients.

Approach:
Significant research progress will result from an approach that a) increases the capability for measuring tannins and their effects in soil ecosystems; b) provides fundamental information about how tannins and other plant-derived polyphenolic compounds interact with soil and affect the basic fluxes and transformations of SOM and the availability of important plant nutrients such as nitrogen and phosphorus; and c) contributes to synthesis of existing and new data into useful information that provides a rational basis for developing management strategies for soil nutrients. Increasing the capabilities for measuring the effects of tannins and their effects on soil will be achieved through training for USDA-ARS personnel and access to experts in tannin chemistry. Training will provide both a means for analyzing the quantities and qualities of tannins useful in lab and field and also for the partial purification of materials needed for specific research questions. Fundamental information will be established through a systematic series of experiments, conducted primarily at the Appalachian Farming Systems Research Center (AFSRC) to determine if tannins form or mediate the formation of stable organo-mineral complexes in model and soil systems. Representative hydrolyzable and condensed tannins will be determined, procured combined with C and N-containing compounds similar to those known to be important in soil. Test compounds will represent a range of substrate complexities from simple sugars and inorganic N to polysaccharides and amino-containing compounds. Formation and characteristics of tannin-substrate mixtures will be evaluated in first solutions, then in a simplified model soil composed of clay-sized minerals and finally in soil. Results will provide new knowledge about the interactions between tannins and soil factors needed by scientists and extension agents to adapt soil management practices that enhance the storage of SOM and plant nutrient availability. Existing and new data will be synthesized into a framework of functional definitions that relate specific tannin chemistry to more generic functions that in turn can be classed as both measurable and manageable regulators of SOM, P, and/or N transformations in the rhizosphere of Appalachian agroecosystems to provide managers with a functional basis for developing management strategies for soil nutrients.